Continuing high frequency energy ignition system with improvements

ABSTRACT

In connection with an ignition system that employs continuing high frequency energy for supplying a spark having a predetermined duration, there are relay controlled circuits for adding and removing resistances that will shift the circuit gain and compensate against a change in frequency.

United States Patent Inventor Robert E. Canup Richmond, Va.

Appl. No. Filed Patented Assignee May 1, 1970 Sept. 28, 1971 Texaco Inc.

New York, N.Y.

CONTINUING HIGH FREQUENCY ENERGY 1 IGNITION SYSTEM WITH IMPROVEMENTS Primary Examiner-Laurence M. Goodridge Attorneys-Thomas I-I. Whaley and Carl C. Reis ABSTRACT: In connection with an ignition system that em- 1 Drawing ploys continuing high frequency energy for supplying a spark U.S.Cl. 123/148 E, having a predetermined duration, there are relay controlled 315/206 circuits for adding and removing resistances that will shift the Int. Cl. F02p 3/02 circuit gain and compensate against a change in frequency.

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CONTINUING HIGH FREQUENCY ENERGY IGNITION SYSTEM WITH IMPROVEMENTS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention concerns ignition systems generally and particularly an ignition system of the type that supplies continuing high frequency energy to the spark gaps. More specifically, it concerns an improvement for such type of ignition system. I

2. Description of the Prior Art Ignition systems that employ continuing duration high frequencyenergy for the spark supply, have not found very wide spread acceptance for various reasons. One problem that has been encountered is especially evident in such a system when a 24-volt battery is used. The battery is charged when the engine is running, and, on the other hand it supplies current to the starter motor during starting conditions. Consequently, there is a large swing in battery terminal voltage.

SUMMARY OF THE INVENTION Briefly, this invention pertains to an ignition system for use with an internal combustion engine which has breaker points associated therewith for mechanically determining the timing of initiation of an ignition spark for a cylinder of said engine. The system also has an oscillator employing transistors and electromagnetic feedback coupling and provides relatively high frequency electrical energy having continuous duration during oscillation thereof. In addition, the system has means for saturating said feedback coupling with steady state mag.- netic flux to stop said oscillation, and has means under control of said breaker points for cutting off said steady state magnetic flux in order to cause rapid starting of said high frequency energy. Finally, the system also includes a DC power supply voltage subject to relatively large variation. In connection with the foregoing system, the invention relates to the improvement which comprises first resistor means for limiting the power dissipated in said transistors, and second resistor means in said feedback coupling for determining the frequency of said oscillator when said voltage is low. The improvement also comprises means for switching out said first resistor means and switching in said second resistor means when said voltage is low, in order to increase the circuit gain without increasing the frequency of the oscillation.

BRIEF DESCRIPTION OF THE DRAWING The foregoing and other objects and benefits of the invention will be more fully set forth in connection with the best mode contemplated by the inventor of carrying out the invention, and in connection with which there are illustrations provided in the drawings, wherein:

The FIGURE of drawings shows a circuit diagram illustrating an ignition system according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT It will be appreciated that this invention concerns an improvement for the type of ignition system that supplies a continuing high frequency energy source during the entire period of a spark discharge. Such system is, of course, particularly applicable to internal combustion engines.

An illustration of a continuing frequency energy system of the type under consideration is to be found in US Pat. No. 3,407,795 to R. W. Aiken et al. issued Oct. 29, 1968. And, this invention is illustrated as applied to an ignition system like that disclosed in the Aiken et al. patent. The invention pertains particularly to an improvement which is beneficial under hard starting conditions, such as those encountered in very low temperatures where the power drain on the battery becomes so great that the output voltage of the battery may fall to a low level. For example, in a 24-v0lt battery system the starting voltage at the battery terminals may fall to aslow as about l8'volts.

Another facet of the problem relates to the concomitant fact that under running conditions, i.e. while the battery is being charged, its terminal voltage may rise above normal to as high as 28 or 29 volts. Therefore, the problem is one of having the system able to accept the wide limit of voltage spread without damage to the various elements, such as the transistors of the oscillator that is employed.

Referring now to the FIGURE of drawings, it is pointed out that the system is basically like that disclosed in the Aiken et al. patent. There is an output transformer 11 that has an output winding 12 which is connected to the spark distributor and thereafter the spark plugs, as indicated by the caption. Transformer 11 also has a center-tapped input winding 15. This winding is connected at the ends thereof to the emitter terminals respectively of a pair of transistors 16 and 17. These connections will be traced in more detail hereafter. A center tap connection 20 on the winding 15 is connected via a circuit connection 21 to a common point 24 to which a source of DC potential is connected when the system is energized, as will appear in more detail hereafter.

There is a feedback transformer 23 that has an oscillation control or saturation winding 22, in addition to three other windings 25, 26 and 27. These windings along with the transistors 16 and 17 and the two halves of the center tapped winding 15 of the output transformer 11, are parts of the oscillator which supplies the continuing high frequency electrical energy for the duration of the spark intervals in the manner described in the aforementioned Aiken et al. patent.

It is pointed out that in accordance with this invention there are included in the basic oscillating circuit some added elements. These are in general for determining the conditions in the oscillator under alternative states of operation. Thus, there are included in the emitter connections of the transistors 16 and 17, resistors 30 and 31, respectively. These are connected between the emitter terminal and the corresponding end of winding 15 on transformer 11, in each case. They are chosen so that with the parameters of the transformers I1 and 23 there will be an adequate spark as to breakdown of the gap and supplying enough current to ignite the fuel, while limiting the amount of power dissipated in the transistors 16 and 17 to a safe value which will not exceed their power ratings with the maximum voltage input.

However, when the engine is started there is a relay 34 that is operated by a solenoid 35, which is connected for energization in parallel with a starting solenoid 36 that controls the contacts in a starter circuit 37, as indicated by the caption. As will appear in more detail below, the relay 34 acts during starting to remove the resistors 30 and 31 so as to prevent the output voltage from transformer 11 from falling too low during the time when the terminal voltage of the battery is pulled down under heavy drain due to starting conditions of the engine.

It will be observed that there is a battery 40 which has one side grounded, i.e., at a ground connection 41. The other side of the battery is connected to one contact terminal of a combination ignition and starter switch 42. This switch 42 is indicated by the caption Ignition-Starter Switch (Manually Operated)" and it is a double-pole, three-position switch.

It will be appreciated that the starter switch 42 will act in the conventional manner, with a spring bias (not shown) to the middle position away from the right hand (as viewed in the drawing) position. Furthermore, when the switch is thrown to either the start (right-hand) or run (middle) positions, the battery 40 will be connected into the system to supply electrical energy to the oscillator. This is done via a circuit connection 45 which goes from a switch arm terminal 44 to the common point 24 in the oscillator circuit.

Of course, there is also a circuit from the battery 40 for supplying power to the starter (circuit connection 37). Such circuit goes via a connection 46 that leads to one side of a switch 47 that is actuated by the solenoid 36. Thus, when the switch 42 is thrown to the start (right-hand) position, the solenoid 36 will be energized and the switch 47 closed. At the same time,

the solenoid 35of'the relay 34 will be'energized.

The latter action, i.e. energization of relay solenoids 35 and 36 that are connected in parallel, takes place during a starting period that will be determined by the holding of the switch 42 in its right-hand (start) position against the spring bias. Thereafter, when released the switch 42 will return to its middle position for run conditions.

It will be observed that the relay 34 has a two position switch arm 50 that is actuated simultaneously with two other similar two position switch arms 51 and 52. These are all shown in the deenergized position which is that occupied under run conditions for the system. It will be noted that under such run conditions, switch arms 50 and 52 occupy an open circuit position. This results in the resistors 30 and 31, respectively, being left effectively connected into the emitter circuits of transistors 16 and 17, and the result is to set the oscillator to operate within safe limits (as indicated above) even when the battery terminal voltage is above nonnal such as when the battery is being charged.

On the other hand when the relay 34 is actuated, i.e., under starting conditions, the switch arms 50 and 52 will occupy the other position. in that case a shunt circuit which bypasses or short circuits the resistors 30 and 31 respectively will be connected. The effect of this arrangement is to remove the emitter lead resistors 30 and 31 under starting conditions so that the gain at the oscillator output from transformer 11 will be increased to compensate for the low battery terminal voltage that is encountered during starting conditions.

In order to avoid an increase in the frequency of the oscillator beyond acceptable limits when the emitter lead resistors 30 and 31 are not connected into the circuit, there is a resistor 55 that is added into the oscillator feedback circuit which involves the winding 26 on the saturation transformer 23. Thus, the amount of resistance in that feedback circuit will be increased during the starting conditions by adding the resistance of the resistor 55 to a feedback circuit resistor 56. The circuit for accomplishing this includes the switch arm 51 which will occupy the other position from that illustrated. Thus the short circuit path around resistor 55 is removed. The value of the resistor 56 will have been selected to give a proper frequency so that correct restart characteristics exist at the spark plug gaps.

it may be observed that the basic ignition system employs the saturation winding 22 (on transformer 23) for starting and stopping the oscillator in the manner described in the Aiken et al. U.S. Pat. No. 3,407,795. Energization of this saturation winding is under control of a circuit including a resistor 60 and timing contacts, or points 61. The latter are controlled from a cam 62 that is located at the distributor (not shown) of the engine, in a conventional manner.

It is to be particularly noted that this invention provides a system which is applicable to and is an improvement for a continuous high frequency ignition system. It does provide adequate spark energy power output under high battery voltage conditions, while also including means to switch over and avoid increasing the frequency of the oscillator under low battery voltage conditions. During the latter situation the gain of the system is increased to maintain adequate spark energy under hard starting conditions. At the same time the invention permits close control so that a cost saving may be possible by permitting use of germanium instead of silicon transistors.

While a particular embodiment of the invention has been described above in considerable detail, it is not to be taken as in any way limiting the invention, but as merely being descriptive thereof.

1 claim:

1. In an ignition system for use with an internal combustion engine having breaker points associated therewith for mechanically determining the timing of initiation of an ignition spark for a cylinder of said engine, and having:

1. an oscillator employing transistors and electromagnetic feedback coupling and providing relatively high frequency electrical energy having continuing duration during oscillation thereof.

2. means for saturating said feedback coupling with steady state magnetic flux to stop said oscillator. 3. means under control of said breaker points for cutting off said steady state magnetic flux in order to cause rapid starting of said high frequency energy, and

4. a DC power supply voltage subject to relatively large variation,

the improvement comprising first resistor means for limiting the power dissipated in said transistors of l second resistor means in said feedback coupling of l) for determining the frequency of said oscillation when said voltage (4) is low, and

means for switching out said first resistor means and switching in said second resistor means when said voltage (4) is low in order to increase the circuit gain without increasing the frequency of the oscillation.

2. The invention according to claim 1 wherein said means for switching comprises a relay, and

circuit means connected to said first and second resistor means and including contacts of said relay.

3. The invention according to claim 2 further including means for actuating said relay during starting of said engine.

4. In an ignition system according to claim 1,

the improvement comprising a resistor in series with the emitter of each of said transistors for limiting the power dissipated in the transistors,

another resistor connected in series with the circuit for said electromagnetic feedback coupling,

a relay having switch contacts, and

circuit connections including said switch contacts for short circuiting said first named emitter resistors and for adding more resistance to said feedback coupling resistor,

said relay being connected for actuation simultaneously with the starter for said internal combustion engine. 

1. In an ignition system for use with an internal combustion engine having breaker points associated therewith for mechanically determining the timing of initiation of an ignition spark for a cylinder of said engine, and having:
 1. an oscillator employing transistors and electromagnetic feedback coupling and providing relatively high frequency electrical energy having continuing duration during oscillation thereof,
 2. means for saturating said feedback coupling with steady state magnetic flux to stop said oscillator,
 3. means under control of said breaker points for cutting off said steady state magnetic flux in order to cause rapid starting of said high frequency energy, and
 4. a DC power supply voltage subject to relatively large variation, the improvement comprising first resistor means for limiting the power dissipated in said transistors of (1), second resistor means in said feedback coupling of (1) for determining the frequency of said oscillation when said voltage (4) is low, and means for switching out said first resistor means and switching in said second resistor means when said voltage (4) is low in order to increase the circuit gain without increasing the frequency of the oscillation.
 2. means for saturating said feedback coupling with steady state magnetic flux to stop said oscillator,
 2. The invention according to claim 1 wherein said means for switching comprises a relay, and circuit means connected to said first and second resistor means and including contacts of said relay.
 3. The invention according to claim 2 further including means for actuating said relay during starting of said engine.
 3. means under control of said breaker points for cutting off said steady state magnetic flux in order to cause rapid starting of said high frequency energy, and
 4. a DC power supply voltage subject to relatively large variation, the improvement comprising first resistor means for limiting the power dissipated in said transistors of (1), second resistor means in said feedback coupling of (1) for determining the frequency of said oscillation when said voltage (4) is low, and means for switching out said first resistor means and switching in said second resistor means when said voltage (4) is low in order to increase the circuit gain without increasing the frequency of the oscillation.
 4. In an ignition system according to claim 1, the improvement comprising a resistor in series with the emitter of each of said transistors for limiting the power dissipated in the transistors, another resistor connected in series with the circuit for said electromagnetic feedback coupling, a relay having switch contacts, and circuit connections including said switch contacts for short circuiting said first named emitter resistors and for adding more resistance to said feedback coupling resistor, said relay being connected for actuation simultaneously with the starter for said internal combustion engine. 